Improve mapping SignalServiceAddresses to Recipients.

app/src/main/java/org/thoughtcrime/securesms/util/RecipientAccessList.kt

@@ -0,0 +1,40 @@
+package org.thoughtcrime.securesms.util
+
+import org.thoughtcrime.securesms.recipients.Recipient
+import org.thoughtcrime.securesms.recipients.RecipientId
+import org.whispersystems.signalservice.api.push.SignalServiceAddress
+import java.lang.IllegalArgumentException
+import java.util.UUID
+
+/**
+ * A list of Recipients, but with some helpful methods for retrieving them by various properties. Uses lazy properties to ensure that it will be as performant
+ * as a regular list if you don't call any of the extra methods.
+ */
+class RecipientAccessList(private val recipients: List<Recipient>) : List<Recipient> by recipients {
+
+  private val byUuid: Map<UUID, Recipient> by lazy {
+    recipients
+      .filter { it.hasUuid() }
+      .associateBy { it.requireUuid() }
+  }
+
+  private val byE164: Map<String, Recipient> by lazy {
+    recipients
+      .filter { it.hasE164() }
+      .associateBy { it.requireE164() }
+  }
+
+  fun requireByAddress(address: SignalServiceAddress): Recipient {
+    if (address.uuid.isPresent && byUuid.containsKey(address.uuid.get())) {
+      return byUuid.get(address.uuid.get())!!
+    } else if (address.number.isPresent && byE164.containsKey(address.number.get())) {
+      return byE164.get(address.number.get())!!
+    } else {
+      throw IllegalArgumentException("Could not find a matching recipient!")
+    }
+  }
+
+  fun requireIdByAddress(address: SignalServiceAddress): RecipientId {
+    return requireByAddress(address).id
+  }
+}